This invention relates to disc drives, and particularly to an improved shroud that protects the arm and suspension assembly of the disc drive from wind from a rotating disc for minimizing fly height modulation of an aerodynamic slider.
Certain magnetic, electromagnetic and optical disc drives employ aerodynamic sliders arranged to xe2x80x9cflyxe2x80x9d a predetermined distance from the confronting recording surface of the rotating disc. Wind, caused by the disc rotation, reacts against air bearing surfaces on the slider that is attached to the arm and suspension assembly of the drive, causing the slider, and its transducing head, to xe2x80x9cflyxe2x80x9d the predetermined distance from the recording surface. The wind also strikes the arm and suspension assembly.
The wind velocity changes across the radius of the rotating disc due to the different linear velocity at different radii across the disc. The profile of the arm to the radius of the disc is smaller when the arm positions the head at an outer radius track than when the arm positions the head at an inner radius. Consequently, the velocity of the wind striking the arm and suspension assembly varies with the extent of the arm across the radius, with greatest variation in wind velocity across the arm profile occurring when the arm extends across the disc radius to position the head at an inner track. Moreover, the wind striking the arm and suspension assembly introduces air turbulence that also affects wind velocity. Air turbulence and changing wind velocity striking the arm and suspension assembly may introduce modulation in arm and suspension assembly that is translated by the suspension to the slider to modulate the fly height of the slider. Fly height modulation may adversely affect the flying characteristics of the head and the data transfer characteristics of the transducer carried by the slider. Moreover, as the data storage capacity of disc drives increases, data density increases requiring smaller recording patterns to avoid cross-talk. Smaller recording patterns require the heads to fly at lower fly heights to the recording surface for read and write operations.
Fly height modulation is a limiting factor on decreasing slider fly heights. It is generally accepted that the fly height of a slider should not modulate more than about 10% of the design fly height. Where the design fly height is 10 nanometers, fly height modulation should not exceed 1 nanometer, which is an amount that can be exceeded due to wind striking the arm and suspension assembly. Consequently, there is need for lower fly heights as data storage density continues to increase, thereby increasing the need to minimize fly height modulation.
Various shrouds have been proposed to control wind in a disc drive. Shrouds described in U.S. Patent Nos. 4,473,855 and 4,879,618 are intended to shield the arm from wind. These shrouds are carried on, and movable with, the arm assembly, thereby adding mass to the arm assembly. The increased mass due to the shroud increases the inertia of the arm assembly during track seeking and positioning operations, thereby adversely affecting performance of the disc drive. Numerous shrouds and baffles have been proposed to control air flow in a disc drive without shielding the arm, such as to control air movement at the edge of the disc to prevent disc flutter (U.S. Pat. No. 6,125,003) and to aid in filtering the air (U.S. Pat. No. 5,696,649), to name a few. There has not been an effective shroud that shields the arm and suspension from the wind without adding to the mass of the arm assembly. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.
A shroud has a mount for mounting the shroud to a housing, such as a wall of a disc drive housing of a disc drive having an arm that positions a device, such as a slider, in a windy environment. Shielding means shields the arm from wind while the arm positions the device in the windy environment. In preferred embodiments, the shield includes a first wall defining a windward surface. In other embodiments, a second wall is perpendicular to the first wall, so that the first and second walls together form a low-wind region with an opening into the region at a leeward side allowing the arm in the low-wind region to position the device in the windy environment.
In some embodiments, a third wall perpendicular to the first wall and parallel to the second wall define a low-wind slot for receiving the arm.
The shroud is positioned in the disc drive so that the second and third walls are between the arm and the rotating disc.
Other features and benefits that characterize the present invention will be apparent upon reading the following detailed description and review of the associated drawings.